Php Tag Cloud: Cloud by Array

Code used in screencast

$tags = array();
$keywords = array();
$keywords[] = "Hello World";
$keywords[] = "Hello world Again";
$keywords[] = "Hello Again";
$keywords[] = "Hello Again one more time";
$keywords[] = "Goodbye Seeya";
$keywords[] = "Pencil";
$keywords[] = "Howto sharpen pencil";
$keywords[] = "Drawing paper";
$keywords[] = "Drawing rocks";
 
foreach($keywords as $keyword)
        {
        $words = explode(" ",$keyword);
        foreach($words as $word)
                {
                $word = strtolower($word);
                if (isset($tags[$word]))
                        {
                        $tags[$word] += 1;
                        }
                else
                        {
                        $tags[$word] = 1;
                        }
                }
        }
ksort($tags);
foreach($tags as $tag=>$size)
        {
        $size += 7;
        echo "<span style=\"font-size: {$size}px\">$tag</span> ";
        }